Vector
An ordered list of numbers, representing a point or direction with magnitude.
- Lives in a vector space; supports addition and scalar multiplication.
- Default column vectors in math; 1D arrays in code.
- Features, embeddings, gradients are all vectors.
When to use: Almost every ML quantity: feature row, embedding, parameter gradient, model output.
Example: 3D position [1, 2, 3] in R³. A 768-dim BERT "king" embedding in R^768.